1. Field of the Invention
The present disclosure relates to the technical field of liquid display, in particular to a method for detecting resistance of a photo resist layer.
2. Description of the Related Art
The ion-implantation process is a doping technology for semiconductor material. It means that an ion beam has a speed that is reduced gradually due to resistance of solid material after the ion beam impacts on the solid material and the ion finally is left in the solid material. The ion-implantation process has advantages of low temperature doping, easy masking, accurate dose control and high uniformity. In addition, it may be used in a plurality of process steps, for example, source and drain doping, channel doping, light doping or drain doping. In this way, the resultant semiconductor devices will have properties such as high speed, low power assumption, good stability and high yield. In different ion-implantation processes, the conditions such as the desired energy and doses of the ion beam are different. And the doping is performed in specific areas when the ions are implanted while other positions or the remaining areas are shielded by resist layers such as photo resist. The photo resist layers are most popular. The photo resist layers with different thicknesses have different resistances to the ion-implantation. Low thickness of the photo resist layer may cause the ions to penetrate through the photo resist layer easily while high thickness of the photo resist layer may bring the difficulty of controlling the critical dimension in lithography. Thus, it is desired to select a suitable thickness of the photo resist layer in the ion-implantation.
In the prior art, a method for determining the resistance of a photo resist layer includes the following steps as shown in FIG. 1. In particular, it includes: Step S101 of providing a plurality of test silicon wafers, which are desired because resistance of the photo resist layer in a plurality of areas needs to be determined and each area needs one test silicon wafer; Step S102 of coating the photo resist layers with different thicknesses onto different test silicon wafers; Step S103 of measuring the thickness of the photo resist layers on each of the test silicon wafers; Step S104 of implanting ions with known energy into the silicon wafers coated with the photo resist layers with different thicknesses; Step S105 of removing the photo resist layers on all of the silicon wafers; Step S106 of testing all of the silicon wafers using secondary ion mass spectrum or spectrometer to obtain the ion amount of the respective silicon wafers. If the ion amount on the silicon wafer falls within a permitted range, it will be determined that the thickness of the photo resist layer coated on the silicon wafer is suitable; otherwise, it will be determined that the thickness of the photo resist layer coated on the silicon wafer is not suitable.
As discussed above, in order to determine the resistance or resisting capability of the photo resist layer to the ion-implantation, at least a plurality of test silicon wafers are needed to perform the above operations and then the ion amount on the test silicon wafers need to be measured one by one. Such method has the following defects: on one hand, a great deal of test silicon wafers are needed, which causes undue cost of detecting the photo resist layers, due to the high manufacturing cost of the test silicon wafers; on the other hand, the secondary ion mass spectrometry is a very expensive test means and the production of test samples is complicated and it will take much test time, thereby, the evaluation cost and time may be greatly increased.